1. Field of the Invention
The present invention is a method that uses a dry blending aid in the form of mustard seeds to monitor and evaluate the dry-blending of powders and granular materials. A known proportion of mustard seed to dry blending materials is added to a mixer and mixed together. Samples are taken, the mustard seeds sieved out of the other materials and measured. The proportion of mustard seeds in the sample are then compared with the expected proportion in the total mixture to determine if the dry blending materials are thoroughly mixed.
2. Description of the Related Art
Currently there is no quick and easy way of directly determining whether dry blending mixtures such as cement are thoroughly blended. Thus the operator must make a determination based on past experience and based on lab results from similar mixtures that were previously mixed.
For example, a sample of dry blended cement mixture is taken from the mixer after a given time interval and taken to the laboratory where it is mixed with water and allowed to harden. The time required for the mixture to harden is an indirect indication of whether the dry blended cement was adequately mixed.
Obviously because of the length of time required to do this type of laboratory work on a sample, in commercial cement mixing operation the mixture upon which the sample was taken will have already been removed from the mixer and new batches will have been mixed. For this reason, this type of testing procedure is not adequate when a new custom blend is being made. In those situations, the blend time needed to thoroughly mix the components might be more or less than the time required for previously tested mixtures having different components.
The present invention addresses this problem by providing a fast and easy way of obtaining a direct measure of the degree of mixing that has occurred in a dry blending mixture. This invention is based on the principal that if one component in the mixture is thoroughly mixed, then all components in the mixture should also be thoroughly mixed. The present invention adds mustard seed as a blending aid in the mixture to be blended. The mustard seed is added at a known concentration to the dry blending mixture and then the mixture is mixed. A sample of the mixture is then obtained and the mustard seeds separated from the other dry mixture components. The mustard seeds are then weighed or counted and the concentration of mustard seeds in the sample is obtained and compared with the theoretical or expected concentration that should be present in the mixture if the mixture is thoroughly mixed. If the concentration of mustard seed in the sample matches the expected concentration, then the mixture is thoroughly mixed. Mustard seeds are inert and non-hazardous and do not affect the properties of the finished mixture. They are therefore a good choice as an indicator of whether the components of the mixture have been adequately mixed.